Excess Electrons, Milikan Oil Drop

I am writing out the lab for the Milikan Oil Drop experiment and punching out the numbers has shown that my measured charge is off by a factor of 5 from the theoretical amount.
theoretical: 1.6e-19
experimental: 3.16e-14

See if I divide this number by 2e5 (which means I am saying there are 200,000 excess electrons on the oil droplet) then I get 1.58e-19 which is really close to theoretical...a little too close.

Question: What is the max number of excess electrons that could plausibly be on an oil droplet. The higher the number the better :).

I am thinking 50. Searched for answers on the internet but to no avail.